Field of the Invention
The invention relates to a flexible vinyl chloride resin composition. More specifically, the invention relates to a flexible vinyl chloride resin composition of a molded product having excellent surface smoothness and excellent flexibility even under the condition of high production speed, a molded product thereof, an electric wire coating material, and a coated electric wire.
Description of Related Art
The vinyl chloride resin has excellent chemical/physical properties such as chemical resistance, weather resistance, flame retardance, and electrical insulation, and is inexpensive, and therefore is extensively applied as a common resin material having high usability. Since the flexible vinyl chloride composition has excellent properties, or flexibility . . . etc. can be readily provided via the addition of a plasticizer, the flexible vinyl chloride composition is applied in many areas in, for instance, coated electric wires, sheet materials, in particular flooring materials, tapes, and films for agriculture in particular.
Moreover, the vinyl chloride resin is inexpensive, and therefore currently production for the object of further increasing productivity at higher production speed while keeping the product cost down is underway.
However, during the molding process under the condition of high production speed, the retention and kneading time of the resin inside the molding machine is very short, and therefore melting and kneading readily become insufficient. Moreover, since the allowable molding conditions of the vinyl chloride resin are limited, a satisfactory molded product cannot be readily obtained by only changing the mold processing conditions.
In particular, the production speed of flexible molding containing a plasticizer is greater compared to hard molding without a plasticizer, and a new method capable of improving kneading state is desired to meet the demand of greater production speed.
In general, to improve the kneading state of the vinyl chloride resin, various methods in which an acrylic resin having a high molecular weight is added for the objects of facilitating melting and providing melt viscosity have been proposed.
For instance, patent literature 1 to patent literature 3 disclose: by adding an acrylic resin having methyl methacrylate as the main component and used as a processing aid in a vinyl chloride resin coated electric wire, processability and dispersibility can be increased.
Moreover, patent literature 4 discloses: by adding an acrylic resin as a modifier in a flexible vinyl chloride resin, a molded product suitable for a metal coating and having excellent shape conformability can be obtained.
However, a molded product having, for instance, satisfactory smooth surface cannot be obtained under the condition of high production speed. Moreover, since flexibility is degraded by adding a high-glass transition temperature component, current techniques are insufficient.
Based on the above, a flexible vinyl chloride resin composition capable of forming a molded product having excellent surface smoothness and excellent flexibility even under the condition of high production speed is desired.